The perk provides its user with general invisibility to UAV Recon, Advanced UAV, Portable Radar, Thermal Scopes, and Heartbeat Sensors. Assassin Pro not only renders the player immune to Counter-UAVs, EMPs and MOABs (meaning one's radar is not jammed nor does a user suffer from electronics failure) but also prevents an enemy aiming at the player from being shown a red crosshair and the player's name (which directly makes Marksman useless against the player). Although enemy Counter-UAVs do not jam the radar with Assassin Pro, any friendly UAVs do not work during the Counter-UAV. Likewise, the player may not call in Pointstreaks during an enemy EMP despite being visually unaffected, and all sorts of killstreaks are destroyed by an EMP even if the player using them has the Pro version.

Assassin is very effective on any stealth build in conjunction with a silencer, allowing one to remain unaffected by enemy surveillance but also become invisible on radar when firing. When combined with a ghillie suit, players carrying sniper rifles will be almost undetectable.

Assassin or its Pro version does not protect the player from being tagged by Recon or the Recon Drone. However, these problems can be minimized, but not entirely eliminated, when used in conjunction with Blind Eye and Dead Silence.[1]